[3/3] TTY/slave: add driver for w2sg0004 GPS

Message ID	20141211215944.4127.57146.stgit@notabene.brown
State	Needs Review / ACK, archived
Headers	show Return-Path: <devicetree-owner@vger.kernel.org> From: NeilBrown <neilb@suse.de> To: Grant Likely <grant.likely@linaro.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mark Rutland <mark.rutland@arm.com>, Jiri Slaby <jslaby@suse.cz> Date: Fri, 12 Dec 2014 08:59:44 +1100 Subject: [PATCH 3/3] TTY/slave: add driver for w2sg0004 GPS Cc: NeilBrown <neil@brown.name>, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20141211215944.4127.57146.stgit@notabene.brown> In-Reply-To: <20141211214801.4127.93914.stgit@notabene.brown> References: <20141211214801.4127.93914.stgit@notabene.brown> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: devicetree-owner@vger.kernel.org Precedence: bulk

Context	Check	Description
robh/checkpatch	warning	total: 1 errors, 1 warnings, 0 lines checked
robh/patch-applied	success

On Fri, 12 Dec 2014 08:59:44 +1100 , NeilBrown <neilb@suse.de> wrote: > This uart-attatched GPS device has a toggle which turns > both on and off. For reliable use we need to know what > start it is in. > > So it registers with the tty for recv events when the tty > is open, and optionally configures the RX pin as a GPIO > interrupt when the tty is closed. > > If it detects data when it should be off, or a lack of data > when it should be on, it toggles the line. > > A regulator can also be configured to power the antenna. > In this case an rfkill device is created. When the rfkill > is 'blocked' or the device is otherwise powered down, > the regulator is turned off. > > Signed-off-by: NeilBrown <neil@brown.name> > --- > .../devicetree/bindings/serial/slave-w2sg0004.txt | 35 ++ > drivers/tty/slaves/Kconfig | 6 > drivers/tty/slaves/Makefile | 3 > drivers/tty/slaves/tty-w2sg0004.c | 412 ++++++++++++++++++++ > 4 files changed, 455 insertions(+), 1 deletion(-) > create mode 100644 Documentation/devicetree/bindings/serial/slave-w2sg0004.txt > create mode 100644 drivers/tty/slaves/tty-w2sg0004.c > > diff --git a/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt b/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt > new file mode 100644 > index 000000000000..c9e7838b3198 > --- /dev/null > +++ b/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt This isn't a binding for a serial device, it is a binding for a GPS device, which happens to be tty attached. Documentation/devicetree/bindings/gps perhaps? > @@ -0,0 +1,35 @@ > +w2sg0004 UART-attached GPS receiver > + > +Required properties: > +- compatbile: "tty,w2sg0004" 'tty' is the wrong prefix. It should be the vendor abbreviation for the GPS vendor. > +- gpios: gpio used to toggle 'on/off' pin > +- interrupts: interrupt generated by RX pin when device should > + be idle > +- pinctrl: "default", "idle" > + "idle" setting is active when device should be off. > + This can remap the RX pin to a GPIO interrupt. > + > +Optional properties: > +- vdd-supply: regulator, e.g. to power antenna > + > + > +The w2sg0004 uses a pin-toggle both to power-on and to > +power-off, so the driver needs to detect what state it is in. > +It does this by detecting characters on the RX line. > +When it should be off, these can optionally be detected by a GPIO. > + > +The node for this device must be the child of a UART. This may need some tweaking to be more portable. ie. if it is wired into a platform with a separate gpio pin also wired to the rx line so that pinctrl manipulation isn't needed. I would make the pinctrl settings optional. > + > +Example: > +&uart2 { > + gps { > + compatible = "tty,w2sg0004"; > + vdd-supply = <&vsim>; > + gpios = <&gpio5 17 0>; /* GPIO_145 */ > + interrupts-extended = <&gpio5 19 0>; /* GPIO_147 */ > + /* When idle, switch RX to be an interrupt */ > + pinctrl-names = "default", "idle"; > + pinctrl-0 = <&uart2_pins>; > + pinctrl-1 = <&uart2_pins_rx_gpio>; > + }; > +}; > diff --git a/drivers/tty/slaves/Kconfig b/drivers/tty/slaves/Kconfig > index 2dd1acf80f8c..7a669faaf02d 100644 > --- a/drivers/tty/slaves/Kconfig > +++ b/drivers/tty/slaves/Kconfig > @@ -9,4 +9,10 @@ if TTY_SLAVE > config TTY_SLAVE_REGULATOR > tristate "TTY slave device powered by regulator" > > +config TTY_SLAVE_W2SG0004 > + tristate "W2SG0004 GPS on/off control" > + help > + Enable on/off control of W2SG0004 GPS when attached > + to a UART. > + Drivers/gps maybe? Do we have any other gps drivers in-tree? > endif > diff --git a/drivers/tty/slaves/Makefile b/drivers/tty/slaves/Makefile > index e636bf49f1cc..ba528fa27110 100644 > --- a/drivers/tty/slaves/Makefile > +++ b/drivers/tty/slaves/Makefile > @@ -1,2 +1,3 @@ > > -obj-$(CONFIG_TTY_SLAVE_REGULATOR) += tty-reg.o > +obj-$(CONFIG_TTY_SLAVE_REGULATOR) += tty-reg.o > +obj-$(CONFIG_TTY_SLAVE_W2SG0004) += tty-w2sg0004.o > diff --git a/drivers/tty/slaves/tty-w2sg0004.c b/drivers/tty/slaves/tty-w2sg0004.c > new file mode 100644 > index 000000000000..7c7ae479bf41 > --- /dev/null > +++ b/drivers/tty/slaves/tty-w2sg0004.c > @@ -0,0 +1,412 @@ > +/* > + * tty-w2sg0004.c - tty-slave for w2sg0004 GPS device > + * > + * Copyright (C) 2014 NeilBrown <neil@brown.name> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * The w2sg0004 is turned 'on' or 'off' by toggling a line, which > + * is normally connected to a GPIO. Thus you need to know the current > + * state in order to determine how to achieve some particular state. > + * The only way to detect the state is by detecting transitions on > + * its TX line (our RX line). > + * So this tty slave listens for 'recv' events and deduces the GPS is > + * on if it has received one recently. > + * If suitably configure, and if the hardware is capable, it also > + * enables an interrupt (presumably via a GPIO connected to the RX > + * line via pinctrl) when the tty is inactive and treat and interrupts > + * as an indication that the device is 'on' and should be turned 'off'. > + * > + * Driver also listens for open/close and trys to turn the GPS on if it is > + * off and the tty is open. On final 'close', the GPS is then turned > + * off. > + * > + * When the device is opened, the GPIO is toggled immediately and then > + * again after 2 seconds of no data. If there is still no data the > + * toggle happens are 4, 8, 16 seconds etc. > + * > + * When the device is closed, the GPIO is toggled immediately and > + * if interrupts are received after 1 second it is toggled again > + * (and again and again with exponentially increasing delays while > + * interrupts continue). > + * > + * If a regulator is configured (e.g. to power the antenna), that is > + * enabled/disabled on open/close. > + * > + * During system suspend the GPS is turned off even if the tty is > + * open. No repeat attempts are made. > + * Possibly it should be possible to keep the GPS on with some > + * configuration. > + */ > + > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <linux/err.h> > +#include <linux/regulator/consumer.h> > +#include <linux/gpio.h> > +#include <linux/of_gpio.h> > +#include <linux/interrupt.h> > +#include <linux/platform_device.h> > +#include <linux/tty.h> > +#include <linux/delay.h> > +#include <linux/pm_runtime.h> > +#include <linux/rfkill.h> > + > +struct w2sg_data { > + int gpio; > + int irq; /* irq line from RX pin when pinctrl > + * set to 'idle' */ > + struct regulator *reg; > + > + unsigned long last_toggle; /* jiffies when last toggle completed. */ > + unsigned long backoff; /* jiffies since last_toggle when > + * we try again > + */ > + enum {Idle, Down, Up} state; /* state-machine state. */ > + bool requested, is_on; > + bool suspended; > + bool reg_enabled; > + > + struct delayed_work work; > + spinlock_t lock; > + struct device *dev; > + > + struct rfkill *rfkill; > +}; > + > +/* > + * There seems to restrictions on how quickly we can toggle the > + * on/off line. Data sheets says "two rtc ticks", whatever that means. > + * If we do it too soon it doesn't work. > + * So we have a state machine which uses the common work queue to ensure > + * clean transitions. > + * When a change is requested we record that request and only act on it > + * once the previous change has completed. > + * A change involves a 10ms low pulse, and a 10ms raised level. > + */ > + > +static void toggle_work(struct work_struct *work) > +{ > + struct w2sg_data *data = container_of( > + work, struct w2sg_data, work.work); > + > + spin_lock_irq(&data->lock); > + switch (data->state) { > + case Up: > + data->state = Idle; > + if (data->requested == data->is_on) > + break; > + if (!data->requested) > + /* Assume it is off unless activity is detected */ > + break; > + /* Try again in a while unless we get some activity */ > + dev_dbg(data->dev, "Wait %dusec until retry\n", > + jiffies_to_msecs(data->backoff)); > + schedule_delayed_work(&data->work, data->backoff); > + break; > + case Idle: > + if (data->requested == data->is_on) > + break; > + > + /* Time to toggle */ > + dev_dbg(data->dev, "Starting toggle to turn %s\n", > + data->requested ? "on" : "off"); > + data->state = Down; > + spin_unlock_irq(&data->lock); > + gpio_set_value_cansleep(data->gpio, 0); > + schedule_delayed_work(&data->work, > + msecs_to_jiffies(10)); > + return; > + > + case Down: > + data->state = Up; > + data->last_toggle = jiffies; > + dev_dbg(data->dev, "Toggle completed, should be %s now.\n", > + data->is_on ? "off" : "on"); > + data->is_on = ! data->is_on; > + spin_unlock_irq(&data->lock); > + > + gpio_set_value_cansleep(data->gpio, 1); > + schedule_delayed_work(&data->work, > + msecs_to_jiffies(10)); > + return; > + } > + spin_unlock_irq(&data->lock); > +} > + > +static irqreturn_t tty_w2_isr(int irq, void *dev_id) > +{ > + struct w2sg_data *data = dev_id; > + unsigned long flags; > + > + spin_lock_irqsave(&data->lock, flags); > + if (!data->requested && !data->is_on && data->state == Idle && > + time_after(jiffies, data->last_toggle + data->backoff)) { > + data->is_on = 1; > + data->backoff *= 2; > + dev_dbg(data->dev, "Received data, must be on. Try to turn off\n"); > + if (!data->suspended) > + schedule_delayed_work(&data->work, 0); > + } > + spin_unlock_irqrestore(&data->lock, flags); > + return IRQ_HANDLED; > +} > + > +static int tty_w2_runtime_resume(struct device *slave) > +{ > + struct w2sg_data *data = dev_get_drvdata(slave); > + unsigned long flags; > + > + if (!data->reg_enabled && > + data->reg && > + !rfkill_blocked(data->rfkill)) > + if (regulator_enable(data->reg) == 0) > + data->reg_enabled = true; > + > + spin_lock_irqsave(&data->lock, flags); > + if (!data->requested) { > + dev_dbg(data->dev, "Device open - turn GPS on\n"); > + data->requested = true; > + data->backoff = HZ; > + if (data->irq) { > + disable_irq(data->irq); > + pinctrl_pm_select_default_state(slave); > + } > + if (!data->suspended && data->state == Idle) > + schedule_delayed_work(&data->work, 0); > + } > + spin_unlock_irqrestore(&data->lock, flags); > + return 0; > +} > + > +static int tty_w2_rfkill_set_block(void *vdata, bool blocked) > +{ > + struct w2sg_data *data = vdata; > + > + dev_dbg(data->dev, "rfkill_set_blocked %d\n", blocked); > + if (blocked && data->reg_enabled) > + if (regulator_disable(data->reg) == 0) > + data->reg_enabled = false; > + if (!blocked && > + !data->reg_enabled && data->reg && > + !pm_runtime_suspended(data->dev)) > + if (regulator_enable(data->reg) == 0) > + data->reg_enabled = true; > + return 0; > +} > + > +static struct rfkill_ops tty_w2_rfkill_ops = { > + .set_block = tty_w2_rfkill_set_block, > +}; > + > +static int tty_w2_runtime_suspend(struct device *slave) > +{ > + struct w2sg_data *data = dev_get_drvdata(slave); > + unsigned long flags; > + > + dev_dbg(data->dev, "Device closed - turn GPS off\n"); > + if (data->reg && data->reg_enabled) > + if (regulator_disable(data->reg) == 0) > + data->reg_enabled = false; > + > + spin_lock_irqsave(&data->lock, flags); > + if (data->requested) { > + data->requested = false; > + data->backoff = HZ; > + if (data->irq) { > + pinctrl_pm_select_idle_state(slave); > + enable_irq(data->irq); > + } > + if (!data->suspended && data->state == Idle) > + schedule_delayed_work(&data->work, 0); > + } > + spin_unlock_irqrestore(&data->lock, flags); > + return 0; > +} > + > +static int tty_w2_suspend(struct device *dev) > +{ > + /* Ignore incoming data and just turn device off. > + * we cannot really wait for a separate thread to > + * do things, so we disable that and do it all > + * here > + */ > + struct w2sg_data *data = dev_get_drvdata(dev); > + > + spin_lock_irq(&data->lock); > + data->suspended = true; > + spin_unlock_irq(&data->lock); > + > + cancel_delayed_work_sync(&data->work); > + if (data->state == Down) { > + dev_dbg(data->dev, "Suspending while GPIO down - raising\n"); > + msleep(10); > + gpio_set_value_cansleep(data->gpio, 1); > + data->last_toggle = jiffies; > + data->is_on = !data->is_on; > + data->state = Up; > + } > + if (data->state == Up) { > + msleep(10); > + data->state = Idle; > + } > + if (data->is_on) { > + dev_dbg(data->dev, "Suspending while GPS on: toggling\n"); > + gpio_set_value_cansleep(data->gpio, 0); > + msleep(10); > + gpio_set_value_cansleep(data->gpio, 1); > + data->is_on = 0; > + } > + return 0; > +} > + > +static int tty_w2_resume(struct device *dev) > +{ > + struct w2sg_data *data = dev_get_drvdata(dev); > + > + spin_lock_irq(&data->lock); > + data->suspended = false; > + spin_unlock_irq(&data->lock); > + schedule_delayed_work(&data->work, 0); > + return 0; > +} > + > +static const struct dev_pm_ops tty_w2_pm_ops = { > + SET_SYSTEM_SLEEP_PM_OPS(tty_w2_suspend, tty_w2_resume) > + SET_RUNTIME_PM_OPS(tty_w2_runtime_suspend, > + tty_w2_runtime_resume, > + NULL) > +}; > + > +static bool toggle_on_probe = false; > + > +static int tty_w2_probe(struct platform_device *pdev) > +{ > + struct w2sg_data *data; > + struct regulator *reg; > + int err; > + > + if (pdev->dev.parent == NULL) > + return -ENODEV; > + > + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + reg = devm_regulator_get(&pdev->dev, "vdd"); > + if (IS_ERR(reg)) { > + err = PTR_ERR(reg); > + if (err != -ENODEV) > + goto out; > + } else > + data->reg = reg; > + > + data->irq = platform_get_irq(pdev, 0); > + if (data->irq < 0) { > + err = data->irq; > + goto out; > + } > + dev_dbg(&pdev->dev, "IRQ configured: %d\n", data->irq); > + > + data->last_toggle = jiffies; > + data->backoff = HZ; > + data->state = Idle; > + data->gpio = of_get_named_gpio(pdev->dev.of_node, "gpios", 0); > + if (data->gpio < 0) { > + err = data->gpio; > + goto out; > + } > + dev_dbg(&pdev->dev, "GPIO configured: %d\n", data->gpio); > + spin_lock_init(&data->lock); > + INIT_DELAYED_WORK(&data->work, toggle_work); > + err = devm_gpio_request_one(&pdev->dev, data->gpio, > + GPIOF_OUT_INIT_HIGH, > + "tty-w2sg0004-on-off"); > + if (err) > + goto out; > + > + if (data->irq) { > + irq_set_status_flags(data->irq, IRQ_NOAUTOEN); > + err = devm_request_irq(&pdev->dev, data->irq, tty_w2_isr, > + IRQF_TRIGGER_FALLING, > + "tty-w2sg0004", data); > + } > + if (err) > + goto out; > + > + if (data->reg) { > + data->rfkill = rfkill_alloc("GPS", &pdev->dev, RFKILL_TYPE_GPS, > + &tty_w2_rfkill_ops, data); > + if (!data->rfkill) { > + err = -ENOMEM; > + goto out; > + } > + err = rfkill_register(data->rfkill); > + if (err) { > + dev_err(&pdev->dev, "Cannot register rfkill device"); > + rfkill_destroy(data->rfkill); > + goto out; > + } > + } > + platform_set_drvdata(pdev, data); > + data->dev = &pdev->dev; > + pm_runtime_enable(&pdev->dev); > + if (data->irq) { > + pinctrl_pm_select_idle_state(&pdev->dev); > + enable_irq(data->irq); > + } > + if (toggle_on_probe) { > + dev_dbg(data->dev, "Performing initial toggle\n"); > + gpio_set_value_cansleep(data->gpio, 0); > + msleep(10); > + gpio_set_value_cansleep(data->gpio, 1); > + msleep(10); > + } > +out: > + dev_dbg(data->dev, "Probed: err=%d\n", err); > + return err; > +} > +module_param(toggle_on_probe, bool, 0); > +MODULE_PARM_DESC(toggle_on_probe, "simulate power-on with GPS active"); > + > +static int tty_w2_remove(struct platform_device *pdev) > +{ > + struct w2sg_data *data = dev_get_drvdata(&pdev->dev); > + if (data->rfkill) { > + rfkill_unregister(data->rfkill); > + rfkill_destroy(data->rfkill); > + } > + return 0; > +} > + > +static struct of_device_id tty_w2_dt_ids[] = { > + { .compatible = "tty,w2sg0004", }, > + {} > +}; > + > +static struct platform_driver tty_w2_driver = { > + .driver.name = "tty-w2sg0004", > + .driver.owner = THIS_MODULE, > + .driver.pm = &tty_w2_pm_ops, > + .driver.of_match_table = tty_w2_dt_ids, > + .probe = tty_w2_probe, > + .remove = tty_w2_remove, > +}; > + > +static int __init tty_w2_init(void) > +{ > + return platform_driver_register(&tty_w2_driver); > +} > +module_init(tty_w2_init); > + > +static void __exit tty_w2_exit(void) > +{ > + platform_driver_unregister(&tty_w2_driver); > +} > +module_exit(tty_w2_exit); module_platform_driver() is your friend. :-) > + > +MODULE_AUTHOR("NeilBrown <neilb@suse.de>"); > +MODULE_DESCRIPTION("Serial port device which turns on W2SG0004 GPS"); > +MODULE_LICENSE("GPL v2"); > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html

diff --git a/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt b/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt new file mode 100644 index 000000000000..c9e7838b3198 --- /dev/null +++ b/Documentation/devicetree/bindings/serial/slave-w2sg0004.txt @@ -0,0 +1,35 @@ +w2sg0004 UART-attached GPS receiver + +Required properties: +- compatbile: "tty,w2sg0004" +- gpios: gpio used to toggle 'on/off' pin +- interrupts: interrupt generated by RX pin when device should + be idle +- pinctrl: "default", "idle" + "idle" setting is active when device should be off. + This can remap the RX pin to a GPIO interrupt. + +Optional properties: +- vdd-supply: regulator, e.g. to power antenna + + +The w2sg0004 uses a pin-toggle both to power-on and to +power-off, so the driver needs to detect what state it is in. +It does this by detecting characters on the RX line. +When it should be off, these can optionally be detected by a GPIO. + +The node for this device must be the child of a UART. + +Example: +&uart2 { + gps { + compatible = "tty,w2sg0004"; + vdd-supply = <&vsim>; + gpios = <&gpio5 17 0>; /* GPIO_145 */ + interrupts-extended = <&gpio5 19 0>; /* GPIO_147 */ + /* When idle, switch RX to be an interrupt */ + pinctrl-names = "default", "idle"; + pinctrl-0 = <&uart2_pins>; + pinctrl-1 = <&uart2_pins_rx_gpio>; + }; +}; diff --git a/drivers/tty/slaves/Kconfig b/drivers/tty/slaves/Kconfig index 2dd1acf80f8c..7a669faaf02d 100644 --- a/drivers/tty/slaves/Kconfig +++ b/drivers/tty/slaves/Kconfig @@ -9,4 +9,10 @@ if TTY_SLAVE config TTY_SLAVE_REGULATOR tristate "TTY slave device powered by regulator" +config TTY_SLAVE_W2SG0004 + tristate "W2SG0004 GPS on/off control" + help + Enable on/off control of W2SG0004 GPS when attached + to a UART. + endif diff --git a/drivers/tty/slaves/Makefile b/drivers/tty/slaves/Makefile index e636bf49f1cc..ba528fa27110 100644 --- a/drivers/tty/slaves/Makefile +++ b/drivers/tty/slaves/Makefile @@ -1,2 +1,3 @@ -obj-$(CONFIG_TTY_SLAVE_REGULATOR) += tty-reg.o +obj-$(CONFIG_TTY_SLAVE_REGULATOR) += tty-reg.o +obj-$(CONFIG_TTY_SLAVE_W2SG0004) += tty-w2sg0004.o diff --git a/drivers/tty/slaves/tty-w2sg0004.c b/drivers/tty/slaves/tty-w2sg0004.c new file mode 100644 index 000000000000..7c7ae479bf41 --- /dev/null +++ b/drivers/tty/slaves/tty-w2sg0004.c @@ -0,0 +1,412 @@ +/* + * tty-w2sg0004.c - tty-slave for w2sg0004 GPS device + * + * Copyright (C) 2014 NeilBrown <neil@brown.name> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * The w2sg0004 is turned 'on' or 'off' by toggling a line, which + * is normally connected to a GPIO. Thus you need to know the current + * state in order to determine how to achieve some particular state. + * The only way to detect the state is by detecting transitions on + * its TX line (our RX line). + * So this tty slave listens for 'recv' events and deduces the GPS is + * on if it has received one recently. + * If suitably configure, and if the hardware is capable, it also + * enables an interrupt (presumably via a GPIO connected to the RX + * line via pinctrl) when the tty is inactive and treat and interrupts + * as an indication that the device is 'on' and should be turned 'off'. + * + * Driver also listens for open/close and trys to turn the GPS on if it is + * off and the tty is open. On final 'close', the GPS is then turned + * off. + * + * When the device is opened, the GPIO is toggled immediately and then + * again after 2 seconds of no data. If there is still no data the + * toggle happens are 4, 8, 16 seconds etc. + * + * When the device is closed, the GPIO is toggled immediately and + * if interrupts are received after 1 second it is toggled again + * (and again and again with exponentially increasing delays while + * interrupts continue). + * + * If a regulator is configured (e.g. to power the antenna), that is + * enabled/disabled on open/close. + * + * During system suspend the GPS is turned off even if the tty is + * open. No repeat attempts are made. + * Possibly it should be possible to keep the GPS on with some + * configuration. + */ + +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/regulator/consumer.h> +#include <linux/gpio.h> +#include <linux/of_gpio.h> +#include <linux/interrupt.h> +#include <linux/platform_device.h> +#include <linux/tty.h> +#include <linux/delay.h> +#include <linux/pm_runtime.h> +#include <linux/rfkill.h> + +struct w2sg_data { + int gpio; + int irq; /* irq line from RX pin when pinctrl + * set to 'idle' */ + struct regulator *reg; + + unsigned long last_toggle; /* jiffies when last toggle completed. */ + unsigned long backoff; /* jiffies since last_toggle when + * we try again + */ + enum {Idle, Down, Up} state; /* state-machine state. */ + bool requested, is_on; + bool suspended; + bool reg_enabled; + + struct delayed_work work; + spinlock_t lock; + struct device *dev; + + struct rfkill *rfkill; +}; + +/* + * There seems to restrictions on how quickly we can toggle the + * on/off line. Data sheets says "two rtc ticks", whatever that means. + * If we do it too soon it doesn't work. + * So we have a state machine which uses the common work queue to ensure + * clean transitions. + * When a change is requested we record that request and only act on it + * once the previous change has completed. + * A change involves a 10ms low pulse, and a 10ms raised level. + */ + +static void toggle_work(struct work_struct *work) +{ + struct w2sg_data *data = container_of( + work, struct w2sg_data, work.work); + + spin_lock_irq(&data->lock); + switch (data->state) { + case Up: + data->state = Idle; + if (data->requested == data->is_on) + break; + if (!data->requested) + /* Assume it is off unless activity is detected */ + break; + /* Try again in a while unless we get some activity */ + dev_dbg(data->dev, "Wait %dusec until retry\n", + jiffies_to_msecs(data->backoff)); + schedule_delayed_work(&data->work, data->backoff); + break; + case Idle: + if (data->requested == data->is_on) + break; + + /* Time to toggle */ + dev_dbg(data->dev, "Starting toggle to turn %s\n", + data->requested ? "on" : "off"); + data->state = Down; + spin_unlock_irq(&data->lock); + gpio_set_value_cansleep(data->gpio, 0); + schedule_delayed_work(&data->work, + msecs_to_jiffies(10)); + return; + + case Down: + data->state = Up; + data->last_toggle = jiffies; + dev_dbg(data->dev, "Toggle completed, should be %s now.\n", + data->is_on ? "off" : "on"); + data->is_on = ! data->is_on; + spin_unlock_irq(&data->lock); + + gpio_set_value_cansleep(data->gpio, 1); + schedule_delayed_work(&data->work, + msecs_to_jiffies(10)); + return; + } + spin_unlock_irq(&data->lock); +} + +static irqreturn_t tty_w2_isr(int irq, void *dev_id) +{ + struct w2sg_data *data = dev_id; + unsigned long flags; + + spin_lock_irqsave(&data->lock, flags); + if (!data->requested && !data->is_on && data->state == Idle && + time_after(jiffies, data->last_toggle + data->backoff)) { + data->is_on = 1; + data->backoff *= 2; + dev_dbg(data->dev, "Received data, must be on. Try to turn off\n"); + if (!data->suspended) + schedule_delayed_work(&data->work, 0); + } + spin_unlock_irqrestore(&data->lock, flags); + return IRQ_HANDLED; +} + +static int tty_w2_runtime_resume(struct device *slave) +{ + struct w2sg_data *data = dev_get_drvdata(slave); + unsigned long flags; + + if (!data->reg_enabled && + data->reg && + !rfkill_blocked(data->rfkill)) + if (regulator_enable(data->reg) == 0) + data->reg_enabled = true; + + spin_lock_irqsave(&data->lock, flags); + if (!data->requested) { + dev_dbg(data->dev, "Device open - turn GPS on\n"); + data->requested = true; + data->backoff = HZ; + if (data->irq) { + disable_irq(data->irq); + pinctrl_pm_select_default_state(slave); + } + if (!data->suspended && data->state == Idle) + schedule_delayed_work(&data->work, 0); + } + spin_unlock_irqrestore(&data->lock, flags); + return 0; +} + +static int tty_w2_rfkill_set_block(void *vdata, bool blocked) +{ + struct w2sg_data *data = vdata; + + dev_dbg(data->dev, "rfkill_set_blocked %d\n", blocked); + if (blocked && data->reg_enabled) + if (regulator_disable(data->reg) == 0) + data->reg_enabled = false; + if (!blocked && + !data->reg_enabled && data->reg && + !pm_runtime_suspended(data->dev)) + if (regulator_enable(data->reg) == 0) + data->reg_enabled = true; + return 0; +} + +static struct rfkill_ops tty_w2_rfkill_ops = { + .set_block = tty_w2_rfkill_set_block, +}; + +static int tty_w2_runtime_suspend(struct device *slave) +{ + struct w2sg_data *data = dev_get_drvdata(slave); + unsigned long flags; + + dev_dbg(data->dev, "Device closed - turn GPS off\n"); + if (data->reg && data->reg_enabled) + if (regulator_disable(data->reg) == 0) + data->reg_enabled = false; + + spin_lock_irqsave(&data->lock, flags); + if (data->requested) { + data->requested = false; + data->backoff = HZ; + if (data->irq) { + pinctrl_pm_select_idle_state(slave); + enable_irq(data->irq); + } + if (!data->suspended && data->state == Idle) + schedule_delayed_work(&data->work, 0); + } + spin_unlock_irqrestore(&data->lock, flags); + return 0; +} + +static int tty_w2_suspend(struct device *dev) +{ + /* Ignore incoming data and just turn device off. + * we cannot really wait for a separate thread to + * do things, so we disable that and do it all + * here + */ + struct w2sg_data *data = dev_get_drvdata(dev); + + spin_lock_irq(&data->lock); + data->suspended = true; + spin_unlock_irq(&data->lock); + + cancel_delayed_work_sync(&data->work); + if (data->state == Down) { + dev_dbg(data->dev, "Suspending while GPIO down - raising\n"); + msleep(10); + gpio_set_value_cansleep(data->gpio, 1); + data->last_toggle = jiffies; + data->is_on = !data->is_on; + data->state = Up; + } + if (data->state == Up) { + msleep(10); + data->state = Idle; + } + if (data->is_on) { + dev_dbg(data->dev, "Suspending while GPS on: toggling\n"); + gpio_set_value_cansleep(data->gpio, 0); + msleep(10); + gpio_set_value_cansleep(data->gpio, 1); + data->is_on = 0; + } + return 0; +} + +static int tty_w2_resume(struct device *dev) +{ + struct w2sg_data *data = dev_get_drvdata(dev); + + spin_lock_irq(&data->lock); + data->suspended = false; + spin_unlock_irq(&data->lock); + schedule_delayed_work(&data->work, 0); + return 0; +} + +static const struct dev_pm_ops tty_w2_pm_ops = { + SET_SYSTEM_SLEEP_PM_OPS(tty_w2_suspend, tty_w2_resume) + SET_RUNTIME_PM_OPS(tty_w2_runtime_suspend, + tty_w2_runtime_resume, + NULL) +}; + +static bool toggle_on_probe = false; + +static int tty_w2_probe(struct platform_device *pdev) +{ + struct w2sg_data *data; + struct regulator *reg; + int err; + + if (pdev->dev.parent == NULL) + return -ENODEV; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + reg = devm_regulator_get(&pdev->dev, "vdd"); + if (IS_ERR(reg)) { + err = PTR_ERR(reg); + if (err != -ENODEV) + goto out; + } else + data->reg = reg; + + data->irq = platform_get_irq(pdev, 0); + if (data->irq < 0) { + err = data->irq; + goto out; + } + dev_dbg(&pdev->dev, "IRQ configured: %d\n", data->irq); + + data->last_toggle = jiffies; + data->backoff = HZ; + data->state = Idle; + data->gpio = of_get_named_gpio(pdev->dev.of_node, "gpios", 0); + if (data->gpio < 0) { + err = data->gpio; + goto out; + } + dev_dbg(&pdev->dev, "GPIO configured: %d\n", data->gpio); + spin_lock_init(&data->lock); + INIT_DELAYED_WORK(&data->work, toggle_work); + err = devm_gpio_request_one(&pdev->dev, data->gpio, + GPIOF_OUT_INIT_HIGH, + "tty-w2sg0004-on-off"); + if (err) + goto out; + + if (data->irq) { + irq_set_status_flags(data->irq, IRQ_NOAUTOEN); + err = devm_request_irq(&pdev->dev, data->irq, tty_w2_isr, + IRQF_TRIGGER_FALLING, + "tty-w2sg0004", data); + } + if (err) + goto out; + + if (data->reg) { + data->rfkill = rfkill_alloc("GPS", &pdev->dev, RFKILL_TYPE_GPS, + &tty_w2_rfkill_ops, data); + if (!data->rfkill) { + err = -ENOMEM; + goto out; + } + err = rfkill_register(data->rfkill); + if (err) { + dev_err(&pdev->dev, "Cannot register rfkill device"); + rfkill_destroy(data->rfkill); + goto out; + } + } + platform_set_drvdata(pdev, data); + data->dev = &pdev->dev; + pm_runtime_enable(&pdev->dev); + if (data->irq) { + pinctrl_pm_select_idle_state(&pdev->dev); + enable_irq(data->irq); + } + if (toggle_on_probe) { + dev_dbg(data->dev, "Performing initial toggle\n"); + gpio_set_value_cansleep(data->gpio, 0); + msleep(10); + gpio_set_value_cansleep(data->gpio, 1); + msleep(10); + } +out: + dev_dbg(data->dev, "Probed: err=%d\n", err); + return err; +} +module_param(toggle_on_probe, bool, 0); +MODULE_PARM_DESC(toggle_on_probe, "simulate power-on with GPS active"); + +static int tty_w2_remove(struct platform_device *pdev) +{ + struct w2sg_data *data = dev_get_drvdata(&pdev->dev); + if (data->rfkill) { + rfkill_unregister(data->rfkill); + rfkill_destroy(data->rfkill); + } + return 0; +} + +static struct of_device_id tty_w2_dt_ids[] = { + { .compatible = "tty,w2sg0004", }, + {} +}; + +static struct platform_driver tty_w2_driver = { + .driver.name = "tty-w2sg0004", + .driver.owner = THIS_MODULE, + .driver.pm = &tty_w2_pm_ops, + .driver.of_match_table = tty_w2_dt_ids, + .probe = tty_w2_probe, + .remove = tty_w2_remove, +}; + +static int __init tty_w2_init(void) +{ + return platform_driver_register(&tty_w2_driver); +} +module_init(tty_w2_init); + +static void __exit tty_w2_exit(void) +{ + platform_driver_unregister(&tty_w2_driver); +} +module_exit(tty_w2_exit); + +MODULE_AUTHOR("NeilBrown <neilb@suse.de>"); +MODULE_DESCRIPTION("Serial port device which turns on W2SG0004 GPS"); +MODULE_LICENSE("GPL v2");

[3/3] TTY/slave: add driver for w2sg0004 GPS

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